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[173.198.77.92]) by smtp.gmail.com with ESMTPSA id l66sm10819490pga.30.2020.01.25.10.06.43 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 25 Jan 2020 10:06:45 -0800 (PST) Subject: Re: [PATCH v4 6/7] disas: mips: Add micromips R6 disassembler - infrastructure and 16-bit instructions To: Aleksandar Markovic References: <1579883929-1517-1-git-send-email-aleksandar.markovic@rt-rk.com> <1579883929-1517-7-git-send-email-aleksandar.markovic@rt-rk.com> <779b7b35-16a8-0538-ad87-fac218c93e82@linaro.org> <0d2d0fff-302b-b8e6-cbc6-5c2bb66f1f8e@linaro.org> From: Richard Henderson Message-ID: Date: Sat, 25 Jan 2020 08:06:40 -1000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2607:f8b0:4864:20::443 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , Stefan Hajnoczi , "qemu-devel@nongnu.org" , Aleksandar Markovic , "amarkovic@wavecomp.com" , "aleksandar.rikalo@rt-rk.com" , "aurelien@aurel32.net" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 1/25/20 12:22 AM, Aleksandar Markovic wrote: > > > On Saturday, January 25, 2020, Richard Henderson > wrote: > > On 1/24/20 1:38 PM, Aleksandar Markovic wrote: > > On Friday, January 24, 2020, Richard Henderson > > > >> wrote: > >     The thing I'm concerned about here is any future maintenance of this > file.  One > >     would surely prefer to edit the original decodetree input than this > output. > > > > > > Here is the deal: This dissasembler is meant to reflect the >  documentation of a > > particular ISA, and as the documentation largely stays constant (except > adding > > some insignificant errata), the disassembler will stay virtually constant, we > > wouldn't like even to touch it, and we like it this way. > > No, this is neither right nor proper. > > To review the code in this form is significantly harder than in its decodetree > form.  That is in fact the whole point of the decodetree form: otherwise we'd > still be writing these sorts of parsers by hand. > > While there's no license on this new file (another problem), if as assumed this > is GPL 2+, then you are in violation of the GPL.  From section 3: > >   # The source code for a work means the preferred form of >   # the work for making modifications to it. > > You cannot with a straight face claim that the generated c is the preferred > form for making modifications. > > Finally, suppose we improve decodetree.py, so that it produces code with which > the compiler produces better code, for some metric of better.  We would want > this disassembler to benefit as well. > > > I think you got some things upside-down. A tool developent and usage should be > driven by the needs of users of a tool, and not dictated by the author. Users > should be free to use the tool in any way they seem suitable, including its > modification. That's exactly right, provided that by "tool" you mean QEMU and by "users" you mean everyone downstream of us. Let me state for the record that I object to this generated file being merged in this form, for the reasons I stated above. r~